Add a crate for the nice control API

[badboy]

For now this only supports a minimal interface on top of Glean

let cfg = Configuration {
    data_path,
    application_id: "org.mozilla.glean_core.example".into(),
    upload_enabled: true,
    max_events: None,
};
glean::initialize(cfg)?;
glean::register_ping_type(&PrototypePing);

if glean::send_ping_by_name("prototype") {
    log::info!("Successfully collected a prototype ping");
} else {
    log::info!("Prototype ping failed");
}

[Dexterp37]

Does this need to change or do you want to update the script ?

[badboy]

Does this need to change or do you want to update the script ?

IMO this should not yet be part of the regular release cycle. It's preview after all and we might just scrape it by January
(also means we can iterate faster on the API part than we need to iterate on Glean-core)

[codecov-io]

Codecov Report

Merging #542 into master will decrease coverage by 0.78%.
The diff coverage is 0%.

@@             Coverage Diff              @@
##             master     #542      +/-   ##
============================================
- Coverage     75.61%   74.82%   -0.79%     
+ Complexity      334      333       -1     
============================================
  Files            98      100       +2     
  Lines          5736     5795      +59     
  Branches        715      718       +3     
============================================
- Hits           4337     4336       -1     
- Misses          879      939      +60     
  Partials        520      520

Impacted Files	Coverage Δ	Complexity Δ
glean-core/preview/src/lib.rs	0% <0%> (ø)	0 <0> (?)
glean-core/preview/src/metrics/ping.rs	0% <0%> (ø)	0 <0> (?)
...ozilla/telemetry/glean/debug/GleanDebugActivity.kt	75% <0%> (-0.76%)	6% <0%> (-1%)

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[chutten]

Let's see if I understand this properly: it currently depends on and builds on the existing glean-ffi (with its handle) because I've been unreasonably impatient about getting an API in place before those refactors can manifest? : D

Looks good, I found a few instances of leftovers but nothing blocking.